According to the structure and the shape, yarns are classified into staple yarns, filament yarns, and composite yarns including staple yarns and filament yarns. Wherein, the staple yarns are fiber aggregate with a particular linear density and a particulate twist, arraying orderly in a longitudinal direction, formed by many spinnable natural or synthetic short fibers with different length via procedures of loosing, carding and drawing for weaving various knitting textiles. Presently, the natural fiber sources are limited by nature, high cost and relative low abrasion resistance and tensile strength, and the synthetic fibers are poor in water adsorbent, comfort and flame-retardant. The textile industry urgently demands a kind of satisfying natural fibers.
Leather is manufactured by skin peeled off from an animal body treated with a series of physical mechanic and chemical methods, followed by tanning to form materials resistant to bacteria effect and abrasion, i.e. materials which are constant and resistant to decay and disruption. Prior to tanning, it is skin and rawhide. There are a great number of types of skin, which is a very complex biological tissue. However, the structures of them are similar and are made up of an epidermal layer, a subdermal layer and an endermic tissue lay. The thickness of the epidermal lay is 0.5-5 percent and is formed by arranging cells with various shapes. The thickness of subdermal layer is more than 90 percent and is dense connective tissue, basically formed by weaving collagen fibers and trace amount of elastic fibers and reticular fibers, wherein the collagen fiber is between 95 and 98 percent. The final leather is produced by processing the real skin. The tissue structure of the collagen fibers is arranged as follows: peptide chain-nascent fibril-fiber filament-fibril-microfibril-fiber-fiber bundles. The concept of the collagen fiber according to the present invention means collagen fiber bundles. The subdermal layer, which is basically made up of loosely weaved collagen fibers and trace amount of elastic fiber, is a loose tissue which links the skin and the body of an animal. It is the subdermal layer that the skin is peeled off from the animal. The subdermal layer is removed during the procedure of leather-making, but it is an excellent raw material in the present technology. Other than being woven, the collagen fibers in the subdermal layer are conglutinated and adhered by fiber matrix. Although a great part of fiber matrix is removed during the process of the leather-making, part of fiber matrix still remains. In addition, during the procedure of leather-making, chemical substances, such as acids and bases, and the like have to be used repeatedly to make the surface of the collagen fiber gelled. These fiber matrix-like materials in liquid state function as lubrication, but form adhesives under dry natural state. Therefore, whether it is animal skin or rawhide, collagen fibers not only exist in great amount, but also have much higher adhesive forces than the tensile strength of the collagen fibers under dry natural state. Additionally, the density of adhesive points of collagen fibers in the leather reaches 1˜2 mm apart. The natural weaving structure of collagen fiber in real skin is that the thicker fiber bundles sometimes are divided into several strands of thinner fiber bundles and the resulting thinner fiber bundles sometimes incorporate other fiber bundles to form another larger fiber bundle. In such way, a special tridimensional reticular structure is formed by alternant division and incorporation, intertwining, without the beginning and the end. That collagen fibers are capable to form bundles is one of characteristics which differ from other textile fibers and non-woven fabric and textiles prepared by the same. Therefore, if the leather is loosened by an opener with a single beater or multiple beaters used in the procedure of cotton or wool and non-woven fabric in the current technology or thread waste opener used in processing reused cotton, the collagen fibers are transformed into powder with the length lower than 4 mm, not reaching the length required for spinning. However, for leathers prepared by tanned belly skin, for example cattle, in which the woven of collagen fibers are loose and endermic tissue lays which are removed in the leather-making industry, they can be processed to form dispersing collagen fibers with single strand and without interconnection by using above described various openers. However, the collagen fibers obtained by the method mentioned above are still short, poor in spinnability, only used for producing low-level textiles or as the raw materials for “waste textile”.
The skins of animals are currently used in leather-making. During the leather-making process, only 20-40 percent rawhide is finally processed to form leather, the rest becomes leftover wastes due to various defects, such as brand, crimple, hurt by grass thorns present in rawhide and other reasons. Additionally, a great mount of fractional materials generated during processing the leather products makes the availability of the sources very low. Recently, some leftover materials are opened or smashed under natural state using the current technology to obtain non-spinning fractional fibers with the length lower than several millimeters, and the resulting fractional fibers conjugate other raw materials to produce low value-added products, such as non-woven fabric and regenerated leather, and so on. China Patent application No. 03114089.0 published on Oct. 8, 2003 disclosed a method for preparing real skin filament. However, the yarns described by the said application were prepared by conglutinating the real skin fibers with adhesive solution, which do not belong the same type of products as the yarns processed by the procedure described in the present invention. Additionally, the description of the method is too simple to disclose sufficiently such that persons skilled in the art cannot achieve.